Electrical apparatus



March 19310 G. A. BURNHAM ELECTRICAL APPARATUS Original Filed April- 14 J5: yew-afar.

sulation, if high voltages 3 lower end oi the insulator.

Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE TION OF MASSACHUSETTS ASSIGNOR TO GONDIT ELECTRICAL MASSACHUSETTS, A CORPORA- ELECTRICAL APPARATUS Original application filed April 14, 1926, Serial This invention relates to oil immersed high tension electric switches and is a division of my copending application Serial No. 102,071, filed April 14, 1926.

The terminals of an electric switch must have suflicient spacing to prevent flash-overs between them, and where air is the insulating medium, the terminals must necessarily be spaced widely apart to provide sufiicient inare employed. To provide the requisite spacing with vertically disposed insulating bushings would necessitate switch casings of prohibitive size; so it has been common practice to obtain the desired spacing at the terminal end of the bushing by inclining the bushings outwardly. This construction, while providing an creased spacing at the top of the insulator, must necessarily decrease the spacing at the To a certain extent this may be permissible since the lower exposed terminals of the insulator are immersed in oil; but it is evident that ii the bushings are inclined to any great extent, the

lateral. dimensions of the switch casing must e increased to maintain a safe sp cing of the lower terminals.

In my above named application, I have disclosed an insulator having a vertical lower 3 insulating portion and an inclined upper insulating portion so that the spa .illg of the lower terminals of a pair of such bushings within the switch can be decreased while maintaining a suitably large spacing between the upper terminals of the casings, while keeping down the lateral diniensimis of the enclosing casing. Insaid application, I have also disclosed a construction oi switch wherein the same advantages are accrued but wherein the casing of the switch forms in effect a part of the bent insulator; and the switch so arranged is one of the objects of this invention.

A further object of the invention is generally to improve the construction and operation of electric switches.

The figure is a vertical sectional elevation through an electric switch embodying the invention;

As here shown, the switch embodying this No. 102,071. Divided and this application filed August 20, Serial No. 214,274.

invention comprises a casing having the bottom wall and a top wall disposed in spaced relation above the bottom wall and having two lateral downwardly inclined sections 12. A mechanism well 14 is disposed in the middle of the casing between said top and bottom walls and compartments 16 are located on opposite sides of the mechanism well and the vertical side walls 18 of the casing and between the bottom wall 10 and the inclined top wall sections 12. An oil containing receptacle 20 is disposed beneath the bottom wall and is secured to the casing by supporting rods 22 and the platform 24. The casing is provided with an annular depending wall 26 which encloses said oil receptacle and said supporting rods 22 and is terminated below the bottom of the oil receptacle. An open top receptacle 28 of substantial volume is secured in fluid tight relation about the open bottom of the annular wall 26 and cooperates with said wall to form a fluid tight expansion chamber for the switch.

In accordance with this invention, each of the stationary s vitch members includes a straight tubular insulating member 30 which is disposed vertically beneath said bottom wall 10 of the switch casing and is provided at its upper ends with a metal attaching flange 32 which is cemented thereto. Said flange is secured to the lower face of said bottom wall 10 by bolts 34 in alignment with an opening 36 in said bottom wall. A metal cap 38 is secured, as cemented. to the lower end of the insulating tube 80 and a stud 40 is passed through and fixed in said cap and a contact block 42 is secured to the lower end oi? said stud.

The movable switch member including the bridging member 44 is adapted to engage both of said blocks, to complete the circuit through the switch as is usual practice.

An insulating tube or shell 46 is disposed above said inclined top wall 12 and has cemented to its lower end an attaching flange or ring 48 which is secured to the outer face of said wall by bolts 50 and in alignment with the opening 52 in said wall. Inasmuch as said wall is inclined from the vertical said shell 46 is thus inclined with respect to its cooperating lower insulating shell 30. The upper and lower insulating shells 46 and 30 respectively, in cooperating with the walls of the switch casing, form an insulating bushing having a vertical lower portion and an outwardly inclined upper portion.

The conductor for the bushing as here shown comprises a section of commercial flexible high tension, cables 54 which is dis-. posed within said upper and lower insulating shells 30 and in the compartment 16 of the switch casing. The lower end of the flexible conductor 56 of said cable is connected electrically with the stud 40. The upper end of said conductor is connected with a similar stud 58 which is passed through acap 60 cemented to the upper end of the insulating shell L6. Said stud is externally screwthreaded and is provided with connecting nuts 62 or the equivalent by which a line conductor can be connected to the bushing. The metalsleeve 64 of said cable section occupies the compartment 16 and preferably extends into the upper and lower insidating tubes and is terminated a suitable distance away from the insulator terminals to expose the insulation 66 thereof and prevent flashovers through the interior of the bushing. Said metal sheath 6& preferably is grounded by means of a spring conductor 68 which bears against the sheath and is con nected with the casing,

By the provision of the arrangement above described, the lower ends of the insulators may be relatively closely spaced under the oil so that the casing will be of moderate diameter while providing adequate oil insulation between the casing and the conducting components of the switch. At the same time, the exposed insulator terminals are widely spaced apart in air and thus may be well insulated against flashovers therebet-ween. The construction also is such that economy of manufacture is obtained over the provision of separate insulating bushings. If desired, the insulators and the compartments 18 can be filled with oil thereby to enhance the insulation of the conductor although ordinarily the vinsulation provided by the section of commercial high tension cable is entirely satisfactory.

I claim:

1. An electric switch having an enclosing casing comprising an oil receptacle and a switch frame comprising a cover there-for, said switch frame having a bottom wall and an upper wall spaced fromsaid bottom wall and having portions inclined with respect thereto, apertures in said walls lying in acommon vertical plane, tubular insulators carried independently by said bottom wall and aligned with the openings therein, con tact members carried by t'helower ends of said insulators, insulators carried "by said top wall and upstanding therefrom in diverging relation and aligned with the aperture therein, bent continuous conductors extended through said insulators and the apertures in said walls and having connection with said contact members, and a movable switch member cooperating with said contact members.

2. An electric switch comprising the combination-of an enclosing casing having acover provided :with verticallyspaced, upper and lower walls having openings therein which are disposed in the same general ver tical plane, said upper wall having portions inclined to said bottom wall, insulators. attached to said lower wall in line with the opening therein and depending therebelow, contact members carried by the lower ends of said insulator-bodies, other insulatorbodies attached to said upper wall in, line with the openings therein and extending upwardly thereabove in diverging relation, and bent continuous conductors extended through said insulator-bodies and said wall-openings and connected with said, contact members.

3. In an electric apparatus, the combination of an enclosing casing having an inner and an outer top wall, tubular insulators depending from said inner top wall, said outer top wall having portions inclined toward said inner wall, upstanding tubular insulators carried by said'outer' top wall and extending upwardly thereabove in diverging relation, terminals carried by the free ends of said insulators, and conductors extended through said tubular insulators and the space between said walls and connected with said terminals.

4. In an electric apparatus, the combina tion of an enclosing casing having a horizontal inner top wall, an outer top wall having sloping surfaces, vertically disposed insulators depending from said inner top wall, inclined, upstanding insulators carried by said outer top wall-,terminals carried by the free ends of said insulators, and a conductor extended through each of said tubular insulators and the space bet ween said walls and connected with said terminals.

5. In an electrical apparatus, an enclosing casing having a compartment provided with a horizontal bottom, wall and a verticaly spaced top wall having portions inclined with respect to said bottom wall, said walls having superposed passages therethrough, insulating shells carried by and depending from said bottom wall at the apertures there in, insulating shells carried by and upstanding from the bottom wall at the aperture therein and inclined with respect to said first insulating shells, and a conductor extended through each of said shells and having a bend therein in said compartment and having terminal memb rs a he ends aid. shellsn s imony hereo I ha v ign d my name to this specification.

stones A. BURNHAM'. 

